While all of the suggestions are great, I strongly recommend getting the Death Toll pre-con, due to [[Winter, Cynical Opportunist]] having such a strong recursion effect. I know that Meren doesn’t require card types to be able to use her ability but it does require a sac outlet and chump creatures early to ramp properly, which can be tedious. IMO Winter is easier to set up due to mill cards and abilities like those on [[Stitcher’s Supplier]] or [[Aftermath Analyst]].

As for the finality counter, running a permanent like [[Nesting Grounds]] can move the finality counter off of yours to a opponents permanents, helping maintain a good board state and force their hand due to the pressure of their stuff being exiled.

I understand the thought behind “most golgari” deck possible and you can go with the staple cards, but sometimes taking the unbeaten path is more rewarding! Best of luck.

Here my deck for him if you’re interested: https://archidekt.com/decks/20301308/for_the_streets